Method of washing a textile product and textile product treatment apparatus used therefore

ABSTRACT

There are provided a washing method using a treatment apparatus of the type, such as a liquid current treatment apparatus for treating a textile product by circulating a treating liquid that is capable of effectively washing a textile product in a shorter time, as well as a textile product treatment apparatus used therefore. A textile product  1  is loaded into a treatment tank  4  and a high-temperature treating liquid, which circulates inside and outside of the treatment tank  4 , is brought into contact with the textile product, thus treating the textile product, and then the textile product is washed with a washing water, in which subsequent to the treatment by the high-temperature treating liquid, the high-temperature treating liquid is gradually discharged from the treatment tank  4  while the washing water is gradually supplied into the treatment tank  4 , during which the discharged high-temperature treating liquid is heat exchanged with the supplied washing water, and the amount of the high-temperature treating liquid to be discharged is set to be equal to the amount of the washing water to be supplied so that the amount of liquid within the treatment tank  4  is kept constant.

TECHNICAL FIELD

The present invention relates to a method of washing a textile product, such as a woven fabric, which is to be carried out subsequent to another treatment such as dyeing, and a textile product treatment apparatus used therefore.

BACKGROUND ART

As an apparatus for carrying out a treatment such as dyeing for a textile product, for example, a liquid current treatment apparatus as illustrated in FIG. 4 is generally used. This apparatus has a retention part 2 for a woven fabric 1, and an annular treatment tank 4 connected between the retention part 2 and a transfer passage 3 for the woven fabric 1. The retention part 2 has a bottom portion provided with treating liquid suction portions 5 (three in this Figure), through which a treating liquid is sucked. The sucked treating liquid is heated under control to a given temperature (generally, a maximum temperature for it is set at a high temperature of 100° C. or higher) and returned to a treating liquid injection part 8 mounted at an end of the transfer passage 3 via a circulating pump 6 and a heat exchanger 7, so that the woven fabric 1 is treated with a liquid current thereof, while being transferred.

In this liquid current treatment, the treating liquid has various dyes, other chemical agents or auxiliary agents remaining therein at the time when the treatment has been finished. In addition, it contains as products resulting from fiber polymerization, oligomer, shag and scale generated from the woven fabric 1.

Therefore, when carrying out, for example, polyester deep dyeing, a cooling water is introduced into the heat exchanger 7 subsequent to the finish of this treatment, thereby lowering the temperature of the treating liquid, while circulating the treating liquid; and then once the treating liquid has been lowered to around 80° C., it is kept at this temperature, while hydrosulfite or an alkaline chemical (caustic soda, soda ash or the like) is injected into the treatment tank 4, thereby carrying out a reduction treatment for the aforesaid remaining products. Thus, a so-called reduction cleaning is carried out. Subsequent to this reduction cleaning, the treating liquid is again cooled to around 60° C. and discharged. Then, supplying a washing water (generally, water), water washing and discharging water are repeated several times, thereby washing a fabric product, and then the fabric product is taken out from the treatment tank 4.

However, the above washing method may pose problems of necessitating a long time washing, not realizing a smooth temperature gradient in cooling, causing wrinkles in the textile product, and thus deteriorating the quality of the fiber product. Also, since oligomer and the like, which have been dissolved at high temperature, are again precipitated, left in the treatment tank 4 and adhered thereto, a so-called tank washing is to be frequently carried out, which is very troublesome and thus poses a problem. Therefore, there is a strong demand for solving these problems.

Meanwhile, the present inventors already proposed and put into practical use an all-new washing method for an air current treatment apparatus that carries out a treatment by spraying a gas-liquid mixed fluid of a treating liquid and air current onto a textile product while moving and circulating the textile product within the treatment tank, which method involves discharging the treatment liquid at high temperature, and then supplying a washing water while heat exchanging with the discharged treatment liquid (cf. Patent Document 1).

Patent Document 1: Japanese Patent Application Laid-open No. Hei-8-269863)

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

Accordingly, it is conceivable to apply the washing method in the above air current treatment apparatus to the liquid current treatment apparatus. However, it has been found that since the amount of a treating liquid used in the air current treatment apparatus is small and the apparatuses are different from each other in structure, it is difficult to apply the above washing method to the liquid current treatment apparatus without modification.

The present invention has been conceived in consideration of the above. It is an object of the present invention to provide a washing method using a treatment apparatus of the type, such as a liquid current treatment apparatus for treating a textile product by circulating a treating liquid that is capable of effectively washing a textile product in a shorter time, as well as a textile product treatment apparatus used therefore.

Means for Solving the Problems

In order to achieve the above object, according to a first aspect of the present invention, there is provided a textile product washing method, which includes loading a textile product into a treatment tank, bringing a high-temperature treating liquid, which circulates inside and outside of the treatment tank, into contact with the textile product, thus treating the textile product, and then washing the textile product with a washing water, wherein subsequent to the treatment by the high-temperature treating liquid, the high-temperature treating liquid is gradually discharged from the treatment tank while the washing water is gradually supplied into the treatment tank, during which the discharged high-temperature treating liquid is heat exchanged with the supplied washing water, and the amount of the high-temperature treating liquid to be discharged is set to be equal to the amount of the washing water to be supplied so that the amount of liquid within the treatment tank is kept constant.

According to another aspect of the present invention, there is provided a textile product washing method, in which at the time when the liquid within the treatment tank has been lowered to a given temperature range by the discharge of the high-temperature treating liquid and the supply of the washing water, the washing water is directly supplied into the treatment tank without being heat exchanged with the high-temperature treating liquid, thus washing the textile product.

According to a third aspect of the present invention, there is provided a textile product washing apparatus used for the textile product washing method of the first aspect or second aspect, which includes: a treatment tank into which a textile product is loaded so that the textile product is brought into contact with a treating liquid; a treating liquid circulation passage through which the treating liquid is taken out from the treatment tank to the outside and repeatedly supplied into the treatment tank via a circulation pump and a heat exchanger; a treating liquid discharge conduit that is connected on an intake side of the circulation pump to the treating liquid circulation passage so as to take out a part of the treating liquid from the treating tank and discharge the same to the outside; a washing water supply conduit that is connected on the intake side of the circulation pump and the downstream side of the connection portion of the treating liquid discharge conduit to the treating liquid circulation passage so as to supply a washing water into the treating liquid circulation passage; and a heat exchanger for heat exchanging the treating liquid passing through the treating liquid discharge conduit with the washing water passing through the washing water supply conduit, wherein the amount of the treating liquid to be discharged through the treating liquid discharge conduit and the amount of the washing water to be supplied through the washing water supply conduit are controlled to be equal to each other.

Advantages of the Invention

Specifically, according to the textile product washing method of the present invention, the high-temperature treating liquid used for the treatment is discharged while maintaining high temperature thereof, and during the discharge, it is heat exchanged with a washing water that is supplied into the treatment tank for washing. Thus, it is possible to remarkably increase the temperature in the washing treatment compared with the conventional method and thus produce an excellent washing effect. Therefore, the number of times of washing to be repeated subsequent to the discharge of the high-temperature washing water can be reduced as compared with the conventional method. Since the treating liquid is discharged while maintaining high temperature thereof, oligomer or dyeing residues or the like are kept dissolved in the treating liquid when discharged, and therefore a reduction cleaning treatment required in a conventional polyester deep dyeing or the like can be omitted. Thus, steam or a chemical agent used for increasing the temperature in the reduction cleaning treatment is not required, which contributes to the cost reduction. Since the amount of the oligomer or dyeing residue adhered to the inner wall of the treatment tank and thus remaining in the treatment tank is decreased, there is an advantage in that the workload in maintenance such as cleaning the treatment tank on regular basis is reduced. In addition, since the amount of the high-temperature treating liquid to be discharged is controlled to be equal to the amount of the washing water to be supplied, the amount of liquid circulating in the treatment tank can be kept constant even when the process changes from the dyeing or the like treatment to the washing treatment, and thus the textile product is prevented from being subjected to excessive stress and is provided with a good finish.

Of the above washing methods, according to the washing method that includes directly supplying the washing water into the treatment tank without heat exchanging the washing water with the high-temperature treating liquid, at the time when the liquid within the treatment tank has been lowered to a given temperature range by the discharge of the high-temperature treating liquid and the supply of the washing water, it is possible to lower the liquid to a given low temperature range in a shorter time when the high-temperature treating liquid is cooled to a low temperature range (e.g., when cooling from 80° C. to 60° C.). In addition, since the washing water is directly supplied into the treatment tank, the washing can be carried out simultaneously with the cooling. Thus, the washing efficiency can be further improved. In the conventional method, when the temperature is lowered to a low temperature range, it is difficult to cool in a smooth temperature gradient, and therefore a wrinkle is easy to be caused in the textile product. However, this method of the present invention produces an advantage in that the smooth temperature gradient is created and thus a wrinkle is hardly caused.

The textile product treatment apparatus of the present invention is achieved by merely adding a simple constitutional element to the conventional treatment apparatus, and therefore the above special washing method can be carried out efficiently at low cost.

FIG. 1 illustrates an explanatory view for illustrating a treatment apparatus according to one embodiment of the present invention.

FIG. 2 illustrates an operation schedule according to the above embodiment.

FIG. 3 illustrates an operation schedule according to a conventional treatment apparatus.

FIG. 4 is an explanatory view illustrating a conventional treatment apparatus.

DESCRIPTION OF REFERENCE NUMERALS

1: Woven fabric

4: Treatment tank

6: Circulation pump

7, 14: Heat exchangers

11: Treating liquid discharge conduit

12: Washing water supply conduit

BEST MODE FOR CARRYING OUT THE INVENTION

Now, the description will be made for a best mode for carrying out the present invention.

FIG. 1 illustrates a liquid current treatment apparatus according to one embodiment of the present invention. This apparatus includes a retention part 2 for a woven fabric 1, and an annular treatment tank 4 to which the retention part 2 and a transfer passage 3 of the woven fabric 1 are connected. A treating liquid is sucked through treating liquid suction portions 5 (three in this Figure) provided in a bottom portion of the retention part 2, and circulated via a circulation pump 6 and a heat exchanger 7 to a treating liquid injection part 8 that is disposed at an end of the transfer passage 3, while maintained at a given temperature. Thus, the woven fabric 1 is treated while being transferred by its liquid current.

A treating liquid discharge conduit 11 for taking out a part of the circulating treating liquid and discharging the same to the outside is connected on the intake side of the circulation pump 6 to a treating liquid circulation passage 10 provided with the circulation pump 6 and the heat exchanger 7, and a washing water supply conduit 12 for supplying a washing water into the treating liquid circulation passage 10 is connected on the downstream side of the connection portion thereof via a check valve 13 to the treating liquid circulation passage 10.

Both the treating liquid discharge conduit 11 and the washing water supply conduit 12 extend through a heat exchanger 14, at which the temperature of the high-temperature treating liquid is lowered while the temperature of a room-temperature washing water is increased. The treating liquid discharge conduit 11 and the washing water supply conduit 12 are respectively provided with shut-off valves 15, 16 and fluid meters 17, 18, so that the amount of the treating liquid to be discharged and the amount of the washing water to be supplied can be controlled to be equal to each other. A reference numeral 19 represents a pump for supply of a washing water and a reference numeral 20 represents a water supply valve.

The treatment and washing of a textile product can be made for example in the following manner by using the aforesaid liquid current treatment apparatus. Specifically, in the same manner as a conventional liquid current treatment apparatus, the woven fabric 1 is first loaded into the treatment tank 4, and the treatment is made in the same manner as a regular treatment with the shut-off valves 15, 16 kept closed. Then, upon the finish of the treatment, the water supply valve 20 is opened, the pump 19 is started, and the shut-off valves 15, 16 are opened so that a part of the treating liquid circulating within the treating liquid circulation passage 10 is taken out into the treating liquid discharge conduit 11, and at the same time the washing water is supplied into the treating liquid circulation passage 10. At this moment, they are passed through the heat exchanger 14 so that heat exchanging is made between the high-temperature treating liquid to be discharged and the room-temperature washing water. In addition, the flow control is made by using the fluid meters 17, 18 and the shut-off valves 15, 16 so that the amount of the treating liquid to be discharged and the amount of the washing water to be supplied are controlled to be equal to each other. Whereby, it is possible to carry out the washing while keeping the amount of liquid circulating within the treatment tank 4 (the mixed liquid in which the treating liquid is gradually replaced with the washing water) constant.

Then, at the time when the temperature of the circulating liquid has reached a given low temperature range (e.g., 60° C.), the discharge of the treating liquid and the supply of the washing water are stopped, and the liquid is directly discharged through a liquid discharge port (not shown) provided in the middle of the treating liquid circulation passage 10 according to needs and circumstances, and a fresh washing water is supplied at a constant flow rate, thereby carrying out the washing treatment, then the discharging, the supplying and the washing are again carried out, and then the woven fabric 1 is taken out. Thus, a series of treatments are finished.

According to the above washing method, the heat exchanging between the high-temperature treating liquid to be discharged and the washing water to be supplied allows the temperature in the washing treatment to be remarkably increased than in the conventional method, and hence produces an excellent washing effect. Accordingly, it is possible to reduce the number of times of washing to be repeated subsequent to the discharge of the high-temperature washing water as compared with the conventional method. Since the treating liquid is discharged while keeping the temperature thereof high, oligomer, dyeing residue or the like are kept dissolved in the treating liquid when discharged, a reduction cleaning treatment required in conventional polyester deep dyeing or the like can be omitted. Thus, steam or chemical agents used for increasing the temperature in the reduction cleaning treatment is not required, which contributes to the cost reduction. Since the amount of the oligomer or dyeing residue adhered to the inner wall of the treatment tank or the like and remaining in the treatment tank is decreased, there is an advantage in that the workload in maintenance such as cleaning the treatment tank 4 on regular basis is reduced. In addition, since the amount of the high-temperature treating liquid to be discharged is controlled to be equal to the amount of the washing water to be supplied, the amount of liquid circulating in the treatment tank 4 can be kept constant even when the process changes from the dyeing or the like treatment to the washing treatment, and thus the textile product is prevented from being subjected to excessive stress and is provided with a good finish.

In the present invention, by the “high-temperature treating liquid” is meant a liquid that has been heated by the heat exchanger 7 provided in the treating liquid circulation passage 10 and set at a high temperature compared with the liquid temperature when supplied. This temperature may be appropriately set depending on the type of the treatment, the type of the textile product, or the like.

In the present invention, by the “washing water” is meant water of a lower temperature than the high-temperature treating liquid to such an extent to allow the temperature of the high-temperature treating liquid to be lowered by the heat exchanging with the high-temperature treating liquid. However, the temperature of the washing water is not necessarily limited to a specific temperature, while water of room temperature is usually used. For the purpose of improving the washing effect, or providing a specific texture or function, water having an appropriate chemical agent added thereinto may be used.

Furthermore, in the present invention, as the method for keeping the amount of liquid within the treatment tank 4 constant by setting the amount of the high-temperature treating liquid to be discharged and the amount of washing water to be supplied to be equal to each other, it is not necessary limited to a afore-mentioned method involving carrying out the flow control for both of them by using the fluid meters 17, 18 and the shut-off valves 15, 16, but an appropriate method may be employed. There is conceivable a method in which a liquid level sensor is disposed within the treatment tank 4, and the shut-off valves 15, 16 are controlled to keep the liquid level constant all the time. However, for the liquid current treatment apparatus, the treating liquid is circulated in the treatment tank 4 while having a ruffled surface, and therefore it is difficult to specify the liquid level. In light of this, the control by the combination of the fluid meters 17, 18 and the shut-off valves 15, 16 is preferable.

In the above examples, at the time when the liquid temperature has reached a low temperature range by the discharge of the high-temperature liquid and the supply of the washing water, the discharge of the liquid is carried out while a fresh washing water is supplied at a constant flow rate, thereby carrying out the washing treatment. As another example, at the time when the liquid temperature has been lowered to a middle temperature range (e.g., 80° C.) being higher than the low temperature range at which the liquid can be discharged, the shut-off valve 15 is closed, thereby stopping taking out of the high-temperature treating liquid from the treating liquid discharge conduit 11, and the washing water is directly supplied into the treatment tank 4 at a constant flow rate without being heat exchanged with the high-temperature treating liquid, so that the circulating liquid can be cooled. The washing water is not necessarily supplied at a constant flow rate. In this respect, the amount of the increased liquid within the treatment tank 4 is gradually decreased through a drain valve. Then, at the time when the temperature of the circulating liquid has been reached to a given low temperature range (e.g., 60° C.), the supply of the washing water is stopped, and in the same manner as the above example, the liquid is directly discharged through the liquid discharge port according to needs and circumstances, then a fresh washing water is supplied, thereby carrying out the washing treatment, then the discharging, the supplying and the washing are again carried out, and then the woven fabric 1 is taken out. Thus, a series of treatments are finished.

According to the above method, it is possible to not only lower the liquid temperature to a given low temperature range in a shorter time, but also carry out the washing simultaneously with the cooling since the washing water is directly supplied into the treatment tank 4. Thus, the washing efficiency can be further improved. According to the conventional method, when the liquid temperature is lowered to a low temperature range, it is difficult to realize a smooth temperature gradient in cooling, causing the textile product to be easily wrinkled. However, according to this method, there is an advantage in that a smooth temperature gradient can be realized and hence a wrinkle is hardly caused.

In the present invention, it is not necessary to limit a textile product to be treated to a specific type, but for example, various synthetic fabrics such as polyester, polyamide, acryl or the like fabric, their blended yarn fabric, combined weave fabric or blended knit fabric, or cellulose based fabrics such as cotton fabric, rayon fabric and hemp fabric, their blended yarn fabric, combined weave fabric or blended knit fabric. Any shape of the textile product, or any form such as weaved cloth, knitted cloth, nonwoven cloth or a product (garment) may be used as well.

In the present invention, as the aforesaid apparatus for treating a textile product and carrying out the washing, it is possible to use any type as long as it carries out the treatment by a treating liquid circulating inside and outside of the treatment tank. For example, in addition to the liquid current treatment apparatus as mentioned in the above example, it is possible to use various type of the treatment apparatus, such as a packaging apparatus that treats a filiform textile product by packaging the same into a skein form, cheese form or corn form, a beam treatment apparatus, or a treatment apparatus that treats a textile product formed by such as thread or weaved yarn, or extends the same into a flat shape by a suspension system, then forming it into a laminate, and then treats the textile product in this laminate form. Furthermore, they can be also applied to the air current treatment apparatus.

In the present invention, as the treatment to a textile product, in addition to the dyeing treatment, it is widely applied to various processes, such as a relaxation process, a resin process, a refinery process and the like in an apparatus other than the liquid current treatment apparatus.

Now, the description will be made for an example along with a comparative example.

EXAMPLE Example

The dyeing and washing of a textile product was carried out following the conditions mentioned below by using a liquid current treatment apparatus as illustrated in FIG. 1.

Textile product: polyester woven fabric (plain fabric of polyester yarn 56 dtex/48f) 100 kg

Progress schedule: following FIG. 2

Chemical agents used in the dyeing step:

-   -   Dye compound: 5 kg     -   Dispersing agent (Nicca Sunsalt RM-340, made by Nicca Chemical         Co., Ltd.): 600 g     -   Acetic acid: 600 g

Liquor-goods ratio: 1/12

Comparative Example

The dyeing and washing of a textile product was carried out following the conditions mentioned below by using a conventional liquid current treatment apparatus as illustrated in FIG. 4.

Textile product: same as that of the Example

Progress schedule: following FIG. 3

Chemical agents used in the dyeing step: same as those of the Example

Chemical agents used in a reduction cleaning step:

-   -   NaOH: 1200 g     -   Hydrosulfite: 1200 g

Liquor-goods ratio: Same as that of the Example

By checking the amount of each of steam, cooling water and the like in each of the Example and the Comparative Example, they were summarized as a contrast in the following Table 1.

TABLE 1 Comparative Example Example Reduction Amount Amount Ratio Items Steps Used Total A Used Total B A/B Steam (kg) Heating 264.6 284.6 264.6 292.5 0.97 Kept at 130° C. 20.0 20.0 Kept at 80° C. 0 7.9 Cooling Temperature Lowering 3323 11023 3818 17268 0.64 Water (Litter) Supplying Dyeing process 1200 1200 Water Slow Cooling 0 2500 (Litter) Water Washing 6500 9750 Power (kw) All the Steps 23.6 23.6 29.0 29.0 0.81 Dyeing Dyeing Process 5000 5000 5000 5000 1.00 Component (g) Auxiliary RM340 Same as 600 Cost: 600 Cost: 0.53 Agents (g) the Above JPY555 JPY1053 Acetic Acid Same as 600 600 the Above Reducing NaOH Reduction 0 1200 Agents (g) Cleaning Hydrosulfite Same as 0 1200 the Above

From the above result, according to the Example, it is possible to reduce the amount of any of steam, water, power and chemical agents used, as compared with the Comparative Example. As can be seen from the progress schedules of FIGS. 2 and 3, the time required for washing treatment is greatly shortened, so that great cost-down can be achieved. In addition, the processed product obtained by the method of the Example causes no wrinkles or the like due to the temperature gradient and thus is of a high quality.

Furthermore, the evaluation was made on color fastness to rubbing (according to JIS L0849) and color fastness to water (according to JIS L0846) for each of the processed product obtained by the method of the Example and the processed product obtained by the method of the Comparative Example, and those results were summarized in the following Table 2. For the products of the Example, each of them to which the process was terminated at an intermediate point was evaluated in the same manner.

TABLE 2 Color Fastness Color Fastness to Water to Rubbing Fading Contamination Example From 4-5 5 3-4 High-temperature Liquid Discharging to After the Washing with Direct Cooling After One Time 4-5 5 3-4 Washing After Two Time 5 5 4 Washing Comparative Example 5 5 4

From the above result, it can be seen that the product of the Example (water washing was carried out two times) has a color fastness to rubbing equivalent to the product of the Comparative Example (the processed product by the conventional method; water washing was carried out three times), although the washing for the product of the Example is repeated one less time than for the product of the Comparative Example. 

1. A textile product washing comprising loading a textile product into a treatment tank, bringing a high-temperature treating liquid, which circulates inside and outside of the treatment tank, into contact with the textile product, thus treating the textile product, and then washing the textile product with a washing water, wherein subsequent to the treatment by the high-temperature treating liquid, the high-temperature treating liquid is gradually discharged from the treatment tank while the washing water is gradually supplied into the treatment tank, during which the discharged high-temperature treating liquid is heat exchanged with the supplied washing water, and the amount of the high-temperature treating liquid to be discharged is set to be equal to the amount of the washing water to be supplied so that the amount of liquid within the treatment tank is kept constant.
 2. The textile product washing method according to claim 1, wherein at the time when the liquid within the treatment tank has been lowered to a given temperature range by the discharge of the high-temperature treating liquid and the supply of the washing water, the washing water is directly supplied into the treatment tank without being heat exchanged with the high-temperature treating liquid, thus washing the textile product.
 3. A textile product washing apparatus used for the textile washing method of claim 1, which comprises: a treatment tank into which a textile product is loaded so that the textile product is brought into contact with a treating liquid; a treating liquid circulation passage through which the treating liquid is taken out from the treatment tank to the outside and repeatedly supplied into the treatment tank via a circulation pump and a heat exchanger; a treating liquid discharge conduit that is connected on an intake side of the circulation pump to the treating liquid circulation passage so as to take out a part of the treating liquid from the treating tank and discharge the same to the outside; a washing water supply conduit that is connected on the intake side of the circulation pump and the downstream side of the connection portion of the treating liquid discharge conduit to the treating liquid circulation passage so as to supply a washing water into the treating liquid circulation passage; and a heat exchanger for heat exchanging the treating liquid passing through the treating liquid discharge conduit with the washing water passing through the washing water supply conduit, wherein the amount of the treating liquid to be discharged through the treating liquid discharge conduit and the amount of the washing water to be supplied through the washing water supply conduit are controlled to be equal to each other.
 4. A textile product washing apparatus used for the textile washing method of claim 2, which comprises: a treatment tank into which a textile product is loaded so that the textile product is brought into contact with a treating liquid; a treating liquid circulation passage through which the treating liquid is taken out from the treatment tank to the outside and repeatedly supplied into the treatment tank via a circulation pump and a heat exchanger; a treating liquid discharge conduit that is connected on an intake side of the circulation pump to the treating liquid circulation passage so as to take out a part of the treating liquid from the treating tank and discharge the same to the outside; a washing water supply conduit that is connected on the intake side of the circulation pump and the downstream side of the connection portion of the treating liquid discharge conduit to the treating liquid circulation passage so as to supply a washing water into the treating liquid circulation passage; and a heat exchanger for heat exchanging the treating liquid passing through the treating liquid discharge conduit with the washing water passing through the washing water supply conduit, wherein the amount of the treating liquid to be discharged through the treating liquid discharge conduit and the amount of the washing water to be supplied through the washing water supply conduit are controlled to be equal to each other. 